The invention concerns reciprocating combustion engine with balancing and pre-compression, and more specifically, an internal combustion engine of the type with a thrust crank in which there are mechanisms that simultaneously perform the functions of balancing and pre-compression of the air intake; said engine employing either the petrol cycle or the diesel cycle and indifferently being two- or four-stroke.
The state of the art already comprises internal combustion engines in which the balancing of the rotating masses is carried out by dedicated mechanisms that move synchronously with the rotation of the drive shaft. The state of the art also comprises engines equipped with compression mechanisms that move synchronously with the rotation of the drive shaft.
In fact, for several years there have been two-stroke internal combustion engines with a piston for compressing the flushing air, carried out by a dedicated piston rotated by a right-angle preceding the active piston, which with every cycle pumps the compressed flushing air. These, however, are not balanced, as the throw of the auxiliary piston is rotated 180 degrees with respect to the drive crank, and also the window distribution and the doubled active piston do not yeild acceptable results regarding imposed limitations to avoid pollution of the atmosphere.
Moreover, as in patent application PCT WO90/15917, there is a four-stroke combustion engine with two in-line cylinders and with throw at 180 degrees in which there is an auxiliary cylinder connected to its own crank-shaft with a multiplication ratio of 2:1 with the drive shaft, to perform the compression of the flushing air and to achieve the balancing of the second order forces of inertia, whereas the first order forces of inertia are balanced by the arrangement of the throw at 180 degrees. However, such an engine is of considerable mechanical complexity due to the shaft dedicated to the auxiliary piston, and it imposes performance limits due to the mechanical limits of the auxiliary piston crankshaft, which, in turn, imposes a severe limit on the speed of rotation of the engine.
Furthermore, there are engines with one cylinder positioned at right-angles to another cylinder, both active, which balance each other in regard to first order forces of inertia.
Finally, there are also mechanisms with auxiliary piston rods rotated 90 degrees to the main piston rod, which achieve the balancing of the rotating and reciprocating masses of a single cylinder engine. Regarding the first order forces of inertia: whereby the auxiliary piston rod is guided by a further smaller rod connected to the foot of the auxiliary piston rod which maintains a certain degree of unbalancing in the transverse direction of the drive shaft in that the said smaller rod is guided at its free end by a rocker arm which cannot have the infinite radius theoretically required. This is in direct contrast to the configuration in which both cylinders and therefore both piston rods are active. Consequently, the said configuration limits the use of this balancing mechanism to the specific purpose, increasing manufacturing costs without obtaining further advantages. Also, in the previous configuration of the two cylinders at 90 degrees there is the complexity of a two cylinder engine and operating characteristics which are intrinsically not improvable, in that the cylinders are limited by the relative reciprocal function.
Such state of the art may be subject to considerable improvement regarding the possibility of eliminating the drawbacks described above, achieving an integration of the moving parts which simplify construction and thereby reducing cost and weight, eliminating the drawbacks mentioned previously.
From the foregoing emerges the need to resolve the technical problem of achieving a configuration of parts which in the typical thrust mechanisms of reciprocating combustion engines reduces vibrations caused by the first order forces generated by the movements of the reciprocating masses, and which may at the same time improve the thermodynamic efficiency of the combustion thereby reducing consumption and pollution, and achieving a higher specific power.
The invention resolves the said technical problem by adopting: reciprocating combustion engine with balancing and pre-compression, comprising at least one active cylinder; at least one auxiliary cylinder positioned at right-angles to the active cylinder; the throw of the pistons of the relative cylinders positioned on the same drive shaft; fuel supply organs; the auxiliary cylinder equipped with cylinder head with a one-way valve for air inlet and a one-way valve for air outlet, characterized in that it has the cylinder head of the active cylinder with at least one outlet valve and at least one opening for the inlet of the air into the active cylinder; finally, having the phase of the piston of the auxiliary cylinder preceding the phase of the piston of the active cylinder by 90 degrees.
An embodiment: comprises a single active cylinder and a single auxiliary cylinder, with both piston rods connected to the same throw of the crankshaft.
An embodiment further comprises two active cylinders and one auxiliary cylinder, with the piston rods of the active cylinders and of the auxiliary cylinder all connected to the same throw.
Another embodiment further comprises, as a variant of the previous one: two active cylinders and one auxiliary cylinder, with the piston rods of the active cylinders and of the auxiliary cylinder each connected to its own throw, and the three throw in phase with each other.
Yet another embodiment further comprises two active cylinders and two corresponding auxiliary cylinders with the throw at 180 degrees and each connected to the corresponding piston rod of the active cylinder and of the auxiliary cylinder.
Yet another embodiment further comprises more than one outlet valve in the cylinder head.
Yet another embodiment further comprises in the case of multi-cylinder engines: more than one active cylinder with one corresponding auxiliary cylinder for each active cylinder, with the piston rods of each active cylinder and of the corresponding auxiliary cylinder connected to the same throw.
Still further, another embodiment further comprises in the case of two stroke engines: the said opening for the inlet consisting of a series of flushing apertures made in the liner of the active cylinder.
Still further, another embodiment further comprises an exhaust turbo-compressor device for the air inlet, connected for its supply upstream of the one-way inlet valve and for the exhaust gases downstream of the one or more said outlet valves.
Still further, another embodiment further comprises, to achieve the diesel cycle, the said fuel supply parts consisting, advantageously of a pump-injector positioned on the axis of the cylinder head of each active cylinder.
Finally, yet another embodiment comprises, to achieve the petrol cycle, the said fuel supply organs consisting, advantageously of a fuel injector positioned in the supply tube upstream of the said inlet opening/valve in the cylinder head of the active cylinder; alternatively consisting of a fuel injector which injects the fuel directly into the combustion chamber.
The advantages obtained with this invention are: the single cylinder engine is intrinsically balanced as regards the first order forces of inertia and at the same time the parts that achieve this also achieve the pre-compression of the air intake, without using other parts or specific additional devices.
Also, the configuration with active cylinder and auxiliary balancing and pre-compression cylinder can be used both with the petrol cycle and the diesel cycle, both two- or four-stroke, in that the lubrication system is separate from the air supply and identical in both the two- and four-stroke engines, and this makes it intrinsically ecological.
Furthermore, the greatest advantages are obtained with the diesel cycle, due to the increase in specific power which is comparable with that of a petrol cycle engine without turbo charging. In the case of a two-cylinder four-stroke engine in the configuration with the throw in phase, the torque distribution is more even, without penalizing operation at high speeds of rotation, in that it is intrinsically balanced. In the two-cylinder version with an auxiliary cylinder for each active cylinder and the throw at 180 degrees, also the second order forces of inertia are compensated.
Finally, the adopted configuration is particularly advantageous in a four-stroke petrol cycle engine in which the intake tube feeds the traditional intake valves and the effect of the increased quantity of air pumped by the auxiliary cylinder is theoretically double. The adopted configuration is also highly advantageous when used with the two-stroke diesel cycle, in that the flushing cycle is carried out using the same parts that subsequently are also capable of performing the pre-compression, enabling excellent results to be obtained, in that the flushing is carried with pure air, without losing energy due to partially burned fuel at the exhaust thereby also causing less pollution.